Alfonso XI of Castile

Alfonso XI "the Avenger" of Castile (and X of Leon) (13 August 1311-27 March 1350) was the King of Castile and Leon from 7 September 1313 to 27 March 1350, succeeding Ferdinand IV of Castile and preceding Peter of Castile.

Biography
Alfonso was born on 13 August 1311, the son of King Ferdinand IV of Castile and Constance of Portugal. He was from the House of d'Ivrea, a dynasty of Catholic Castilians. Ferdinand died while Alfonso was one, so his mother and her family assumed the regency over the infant Alfonso. In 1313 his mother died as well, and by 1319 only his grandmother Maria de Molina was his regent. She died on 1 July 1321, and Alfonso's family tore up the kingdom, even as Levantine nobility and the Moors were raiding the kingdom. When Alfonso took the throne, he executed potential threat Juan de Castilla y Haro and took care to ensure that his rule would not be challenged. In 1337 the Battle of Cabra was a great victory for the Castilians and their Portuguese allies over the Nasrid Emirate, and on 30 October 1340 Alfonso defeated the Marinid Emirate at the Battle of Rio Salado. In 1344, Alfonso conquered the Kingdom of Algeciras, but he died of plague during the 1350 fifth siege of Gibraltar.